| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.nemo.compiler.frontend.beam.transform; |
| |
| import org.apache.beam.sdk.coders.Coder; |
| import org.apache.beam.sdk.coders.CoderRegistry; |
| import org.apache.beam.sdk.transforms.Combine; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.Arrays; |
| |
| /** |
| * Wrapper class for {@link Combine.CombineFn}. |
| * When adding input, it merges its accumulator and input accumulator into a single accumulator. |
| * @param <AccumT> accumulator type |
| * @param <Output> output type |
| */ |
| public final class FinalCombineFn<AccumT, Output> extends Combine.CombineFn<AccumT, AccumT, Output> { |
| private static final Logger LOG = LoggerFactory.getLogger(FinalCombineFn.class.getName()); |
| private final Combine.CombineFn<?, AccumT, Output> originFn; |
| private final Coder<AccumT> accumCoder; |
| |
| public FinalCombineFn(final Combine.CombineFn<?, AccumT, Output> originFn, |
| final Coder<AccumT> accumCoder) { |
| this.originFn = originFn; |
| this.accumCoder = accumCoder; |
| } |
| |
| @Override |
| public AccumT createAccumulator() { |
| return originFn.createAccumulator(); |
| } |
| |
| @Override |
| public AccumT addInput(final AccumT accumulator, final AccumT input) { |
| final AccumT result = originFn.mergeAccumulators(Arrays.asList(accumulator, input)); |
| return result; |
| } |
| |
| @Override |
| public Coder<AccumT> getAccumulatorCoder(final CoderRegistry registry, final Coder<AccumT> ac) { |
| return accumCoder; |
| } |
| |
| @Override |
| public AccumT mergeAccumulators(final Iterable<AccumT> accumulators) { |
| return originFn.mergeAccumulators(accumulators); |
| } |
| |
| @Override |
| public Output extractOutput(final AccumT accumulator) { |
| final Output result = originFn.extractOutput(accumulator); |
| return result; |
| } |
| } |